A surgical microscope of the kind referred to above is known from German patent publication 10 2004 049 368 A1. Here, a surgical microscope is described having a binocular tube for main viewing and a binocular tube for secondary viewing. The binocular tube for main viewing and the binocular tube for secondary viewing are mounted on a common surgical microscope base body. The binocular tube for main viewing and the binocular tube for secondary viewing have stereoscopic viewing beam paths. These viewing beam paths pass through a common microscope main objective.
A surgical microscope which includes an OCT-system is described in U.S. Pat. No. 5,795,295.
An OCT-system (Optical Coherence Tomography) permits the non-invasive illustration and measurement of structures within a tissue utilizing optical coherence tomography. As an image providing process, the optical coherence tomography permits especially section images or volume images of biological tissue to be generated with micrometer resolution. A corresponding OCT-system includes a source for time-dependent incoherent and spatially coherent light having a specific coherence length which is guided to a specimen beam path and a reference beam path. The specimen beam path is directed onto the tissue to be examined. Laser radiation, which is radiated back into the specimen beam path because of scatter centers in the tissue, superposes the OCT-system with laser radiation from the reference beam path. An interference signal develops because of the superposition. The position of the scatter centers for the laser radiation in the examined tissue can be determined from this interference signal.
For OCT-systems, the building principles of the “time-domain OCT” and of the “Fourier-domain OCT” are known.
The configuration of a “time-domain OCT” is described, for example, in U.S. Pat. No. 5,321,501 with reference to FIG. 1a at column 5, line 40, to column 11, line 10. In a system of this kind, the optical path length of the reference beam path is continuously varied via a rapidly moving reference mirror. The light from specimen beam path and reference beam path is superposed on a photo detector. When the optical path lengths of the specimen and reference beam paths are coincident, then an interference signal is provided on the photo detector.
A “Fourier-domain OCT” is, for example, described in international patent publication WO 2006/100544 A1. To measure the optical path length of a specimen beam path, light from a reference beam path is superposed onto light from the specimen beam path. In contrast to the time-domain OCT, the light from the specimen beam path and reference beam path is not supplied directly to a detector for a measurement of the optical path length of the specimen beam path but is first spectrally dispersed by means of a spectrometer. The spectral intensity of the superposed signal generated in this manner from specimen beam path and reference beam path is then detected by a detector. By evaluating the detector signal, the optical path length of the specimen beam path can be determined.
The OCT-system of the surgical microscope disclosed in U.S. Pat. No. 5,795,295 contains a component assembly for generating an OCT-scanning beam of short coherent laser radiation and having an analyzing unit for evaluating interference signals. A unit for scanning the OCT-scanning beam is assigned to this component assembly. The unit for scanning includes two scanning mirrors to scan a surgical region with the OCT-scanning beam. The two mirrors can be displaced about two movement axes. In the surgical microscope of U.S. Pat. No. 5,795,295, the OCT-scanning beam is coupled into the illuminating beam path of the surgical microscope via a divider mirror and the OCT-scanning beam is directed with this illuminating beam through the microscope main objective to the object region.